Flanders is one of the few places in Europe where human biomonitoring is governed by legislation. A human biomonitoring study there is commissioned, managed, and funded by the Flemish government, and conducted by the Flemish Institute for Technological Research (VITO). This research consortium includes scientists from all Flemish universities and two Flemish research institutes. The main objective of the Flemish human biomonitoring program is to establish a monitoring network to measure the environmental pollution to which the population is exposed, and to study the relationship between this exposure and its early health effects. During the first phase of this program (2001–2006), the relationship between place of residence in Flanders and differences in exposure to environmental pollution was studied. To translate the results of this study into public policy measures, a phased action plan was developed. The second part of the program (2007–2011) is based on two pillars. First, reference values for a comprehensive list of pollutants will be determined, based on samples representative of the Flemish population. Next, targeted human biomonitoring will be implemented in specific groups particularly affected by environmental pollution, referred to as "hotspots." In both phases of the project, the focus is on transparent communication and consistent interaction between scientists, politicians, authorities, decision-makers, and the general public, following a participatory process. Human biomonitoring requires the participation of volunteers willing to provide blood, urine, or other body tissue samples, which inevitably raises ethical questions. This article explains how communication lies at the heart of these ethical considerations and highlights certain practical challenges in a transnational research context. (R.A.)